Although microwave cooking has experienced substantial growth, many consumers find that foods heated or cooked in a microwave oven do not possess the taste, sight and general appeal that they have come to associate with foods cooked in conventional ovens. A common complaint of consumers is that food cooked by microwave energy lacks the desired degree of browning or crispness. Various attempts have been made to provide microwave cook-in food packages which are adapted to compensate for the inherent lack of food browning associated with microwave cooking but none of these attempts have provided an entirely satisfactory package which is disposable and usable for shipping, selling, storing and serving of the packaged food.
A first approach, as represented by Brastad in U.S. Pat. No. 4,267,420 and Brastad et al in U.S. Pat. No. 4,230,924 uses flexible sheets of microwave interactive materials wrapped closely about individual items of food wherein the interactive material converts at least a portion of the impinging microwave energy into heat for browning the food surface. While flexible dielectric wrapping materials are suitable for foods such as fish sticks, onion rings and various forms of potatoes, fluids such as grease or vapor driven out of a food during heating may create leakage and/or venting problems, especially if the foods are breakfast sausages, or the like which may generate large quantities of such substances during heating. Still further, flexible wrapping is not suitable as a shipping and display container and will, therefore, require an additional outer carton.
A second approach, as represented by Turpin et al in U.S. Pat. No. 4,190,757, uses microwavable packages which do not require the product to be closely wrapped but includes a microwave interactive layer supported on or adjacent one inside container wall for browning the food. A second microwave interactive layer or heating element can be attached to another container wall to brown another surface of the food being heated such as illustrated in FIGS. 3 and 6 of the Turpin et al patent. However, the amount of heat transferred between the interactive layers of these packages and the food being browned may vary over the surface area of the foods due to surface of dimensional irregularities of the food and non-uniform size variation of the food during heating. Substantial variations or impairment of in the browning effect may, thus, occur over the area of the food being heated in these devices.
U.S. Pat. No. 3,591,751 to Goltsos discloses in FIG. 3 a microwave cooking implement including means contacting both the top and bottom surfaces of an article of food for converting microwave energy into heat for browning the food. The upper browning means includes plural metal rods which appear to be gravity biased into contact with the food but there is no suggestion of how such a bulky implement could be incorporated into an outer carton. Goltsos also fails to disclose an implement which is light enough, inexpensive enough and small enough to be incorporated into a food package.
Presently known design approaches have not provided a microwave "cook-in" disposable package for uniformly and conveniently browning or crisping foods which shrink and/or generate fluids during microwave heating. In particular, no such package design has been disclosed wherein the package is inexpensive and convenient to manufacture and wherein the package may be used as a shipping, display and serving implement.